Data replication method, apparatus, and system

1. A data replication method comprising:

obtaining differential data information corresponding to differential data that differentiate a primary device from a secondary device, wherein the differential data information comprises a storage address of the differential data that are located in the primary device and a determining value of the differential data, where the determining value determines when to initiate a snapshot and comprises a ratio of a data amount of the differential data to a bandwidth for replication between a primary volume and a secondary volume;

recording the bandwidth for replication between the primary volume and the secondary volume;

taking a primary snapshot for the primary device when the determining value is less than a preset threshold; and

replicating the differential data to the secondary volume according to the primary snapshot when the determining value is less than the preset threshold.

2. The data replication method of claim 1 , wherein the determining value comprises the data amount of the differential data.

3. The data replication method of claim 1 , further comprising:

generating first snapshot data due to starting of the primary snapshot; and

storing, during the replicating, the first snapshot data in a primary snapshot volume of the primary volume.

4. The data replication method of claim 3 , further comprising:

generating second snapshot data by starting a secondary snapshot for the secondary device; and

storing, while the secondary device receives the differential data, the second snapshot data in a secondary snapshot volume of the secondary device.

5. The data replication method of claim 1 , wherein the snapshot is a copy-on-write (COW) snapshot or a split-mirror snapshot.

6. The data replication method of claim 1 , wherein before the replicating, the data replication method further comprises:

taking a secondary snapshot for the secondary device; and

cancelling the secondary snapshot after the differential data existing when the primary snapshot is started is all replicated to the secondary device.

7. A primary data storage controller comprising:

a memory configured to store a program; and

a processor coupled to the memory and configured to:

obtain differential data information corresponding to differential data that differentiate a primary device from a secondary device, wherein the differential data information comprises a storage address of the differential data that are located in the primary device and a determining value of the differential data, wherein the determining value determines when to initiate a snapshot and comprises a ratio of a data amount of the differential data to a bandwidth for replication between a primary volume and a secondary volume;

record the bandwidth for replication between the primary volume and the secondary volume;

take a primary snapshot for the primary device when the determining value is less than a preset threshold; and

replicate the differential data to the secondary volume according to the primary snapshot when the determining value is less than the preset threshold.

8. The primary data storage controller of claim 7 , wherein the determining value comprises the data amount of the differential data.

9. The primary data storage controller of claim 7 , wherein the processor is further configured to:

generate first snapshot data due to starting of the primary snapshot; and

store, during the replicating, the first snapshot data in a primary snapshot volume of the primary volume.

10. The primary data storage controller of claim 9 , wherein the processor is further configured to:

generate second snapshot data by starting a secondary snapshot for the secondary device; and

store, while the secondary device receives the differential data, the second snapshot data in a secondary snapshot volume of the secondary device.

11. The primary data storage controller of claim 7 , wherein the snapshot is a copy-on-write (COW) snapshot or a split-mirror snapshot.

12. The primary data storage controller of claim 7 , wherein before the replicating, the processor is further configured to:

take a secondary snapshot for the secondary device; and

cancel the secondary snapshot after the differential data existing when the primary snapshot is started is all replicated to the secondary device.

13. A computer program product comprising instructions that are stored on a non-transitory computer-readable medium and that, when executed by a processor, cause a primary data storage controller to:

obtain differential data information corresponding to differential data that differentiate a primary device from a secondary device, wherein the differential data information comprises a storage address of the differential data that are located in the primary device and a determining value of the differential data, wherein the determining value determines when to initiate a snapshot and comprises a ratio of a data amount of the differential data to a bandwidth for replication between a primary volume and a secondary volume;

record the bandwidth for replication between the primary volume and the secondary volume;

take a primary snapshot for the primary device when the determining value is less than a preset threshold; and

replicate the differential data to the secondary volume according to the primary snapshot when the determining value is less than the preset threshold.

14. The computer program product of claim 13 , wherein the determining value comprises the data amount of the differential data.

15. The computer program product of claim 13 , wherein when executed by the processor, the instructions further cause the primary data storage controller to:

generate first snapshot data due to starting of the primary snapshot;

store, during the replicating, the first snapshot data in a primary snapshot volume of the primary volume;

generate second snapshot data by starting a secondary snapshot for the secondary device; and

store, while the secondary device receives the differential data, the second snapshot data in a secondary snapshot volume of the secondary device.

16. The computer program product of claim 13 , wherein the snapshot is a copy-on-write (COW) snapshot or a split-mirror snapshot.

17. The computer program product of claim 13 , wherein before the replicating and when executed by the processor, the instructions further cause the primary data storage controller to:

take a secondary snapshot for the secondary device; and

cancel the secondary snapshot after the differential data existing when the primary snapshot is started is all replicated to the secondary device.

18. The computer program product of claim 13 , wherein when executed by the processor, the instructions further cause the primary data storage controller to obtain a time required for the replication as the ratio.

19. The data replication method of claim 1 , further comprising obtaining a time required for the replication as the ratio.

20. The primary data storage controller of claim 7 , wherein the processor is further configured to obtain a time required for the replication as the ratio.